Iran and Iraq both claimed today that a major battle in their two-month-old war was under way around the plains town of Susangerd, 20 miles inside Iran on the road to Ahwaz, the capital of Tehran's oil-rich Khuzestan Province.

In communiques from their respective capitals in Baghdad and Tehran, the two warring OPEC nations today acknowledged that "heavy fighting was under way on the very outskirts of the city," which, along with half a dozen other Iranian cities in the province, has been besieged by Iraqi tanks and artillery since the first weeks of the war that began in September.

The general command of the Iraqi armed forces, in its 141st communique of the war, said that 217 Iranians had been killed in the last 24 hours of battle around Susangerd, a town known in Arabic as Khafajia. That was almost twice as high as the previous record daily casualty toll claimed during the war.

On Friday, the Iraqis claimed to have killed 35 Iranians around the town in what was described then as an operation of "eliminating enemy pockets of resistance" in the city that Iraq had claimed had been taken early last October.

The so-called pockets of resistance, however, appeared today to be a major Iranian defense force on the outskirts of the city.

Tehran radio today confirmed that a major battle had been under way around Susangerd since Friday afternoon and said that "heavy casualties" -- later reported to be more than 100 Iraqi soldiers -- had been inflicted on the invading Iraqi armed forces and that many of their tank had been knocked out.

Tehran radio said that the Iraqi invaders had gotten within three miles of the city at some points and that in some places hand-to-hand fighting was taking place. The radio, however, denied Iraqi claims to have surrounded the city.

Military analysts here in Baghdad interpreted the renewed Iraqi thrust at Susangerd as a last-ditch attempt to try to capture Ahwaz, the important provincial capital 35 miles to the east, before the winter rains, already falling in the mountains to the north, make further armor movement in the plains difficult until spring.

The capture of Ahwaz would also provide Iraqi President Saddam Hussein with a much-needed psychological victory on the eve of a scheduled Arab summit meeting in neighboring Amman, Jordan.

Ahwaz has been under siege from at least a full Iraqi division inching from the south along the axis of its road to the now-fallen Iranian port of Khorramshahr, along the Shatt-al-Arab waterway.

Despite six weeks of heavy shelling and rocketing -- and various exaggerated Iraqi claims to have overrun the city or at least surrounded it -- the Iranian defenders have slowed the Iraqi Army in the south to a crawl, allowing it to move only 10 miles in the last month. This leaves the Iraqis' front lines still more than five miles south of the city's southern perimeter.

The offensive to overrun Susangerd, to the west of Ahwaz, was viewed by military analysts as a move by the previously stymied Iraqi armed forces to put the squeeze on the provincial capital from the west as well as from the south and to try to cut off Ahwaz's road links with the important military garrison town of Dezful to the north.

With the 11th Arab summit meeting scheduled for Nov. 25 in neighboring Jordan, the capture of Ahwaz would allow Saddam Hussein to go into the conference -- if indeed it is not postponed as several Arab heads of state have requested -- as a victor in the protracted war with Ayatollah Ruhollah Khomeini's revolution-weakened Iran.

The timing of the Susangerd offensive was therefore dictated both by the approaching rains, which could make the Khuzestan plain all but impassable to Iraqi tanks in the next few weeks, as well as by political necessity that would give Saddam Hussein the sort of clout and influence among his fellow Arabs that he has so long coveted.

Saddam Jussein is vigorously insisting that the Arab summit be held as scheduled despite the bitter divisions among the Arab states that his war with Iran has triggered.

Syrian President Hafez Assad, Saddam Hussein's neighbor and political rival, has already demanded that the summit be postponed, a move in which he is supported by Libya, South Yemen and Yasser Arafat's Palestine Liberation Organization.

Most knowledgeable Middle East analysts, basing their assessment on previous summit cancellations at times of great division among the Arab states, are quietly predicting that the summit will not be held, even though Iraq has rallied support for it from as far away as Morocco. Kuwait today was the latest nation to come out in support of holding the summit.

The secretary of the Arab League, Chadli Klibi, meanwhile flew to the Saudi Arabian capital of Riyadh to continue sounding out Arab leaders about the Syrian demand for a postponement.

Meanwhile, the Iraqis also claimed to have killed 65 other Iranian soldiers on other fronts, as well as downing one Phantom jet and two helicopters and destroying 23 assorted vehicles, six rocket launchers and an assorted number of other Iranian military objectives.

The Iraqis claimed that in the latest fighting they lost only 11 soldiers, three tanks, a personnel carrier and a "trench shovel."